基于可靠度优化扭转梁系统开发成本

基于整车可靠度分解,在置信度、可靠度指标要求下,对系统进行可靠度框图分解,得出零部件级的可靠度要求。简要分析载荷谱的线性累加伪损伤,获取零部件一倍寿命伪损伤值,进而得出最优的样本量区间。根据扭转梁系统R97C50的案例要求,比较扭转梁的零件级试验开发成本、系统级试验开发成本、整车级试验开发成本之间的差异,由零部件试验成本固定为基础,得出系统试验的样本量应该控制为不大于2个样本量,达到优化系统试验成本的目的;使用整车级试验去验证系统级可靠度的成本是系统级试验开发成本的20倍。     

Identification of AMR decompressed audio

More and more conversation recordings from phone calls are used as forensic evidence. To decide whether an unknown speech recording comes from mobile phone or not becomes an important issue in digital audio forensics. The communicating conversation recorded by mobile phones is encoded by Adaptive Multi-Rate (AMR) audio codec, which was adopted as the standard speech codec by 3GPP and widely used in GSM and UMTS. Therefore, AMR decompressed audio detection can be used to identify the source of the digital audio recording. Furthermore, it is helpful to locate the forgery position of the splicing AMR decompressed audio for forensic purposes. In this article, we focus on the identification of AMR decompressed audio, namely, given the waveform of an audio, we wish to identify whether it has been previously compressed by AMR codec or not. The artifacts introduced by the AMR codec will help to detect the source of the recordings. Based on our analysis, we find that the sample repetition rate of the AMR decompressed waveform is significantly greater than the regular waveform. Therefore, we employ the sample repetition rate as a feature to identify the AMR decompressed audio. The experimental results show that this feature is robust and effective.     

Factors affecting cell population density during enrichment and subsequent molecular detection of Salmonella enterica and Escherichia coli O157:H7 on lettuce contaminated during field production

The aim of this study was to evaluate the field survival and subsequent detection of Escherichia coli O157:H7 and Salmonella on leafy greens to understand factors that influence their detection by molecular methods. Both applied microorganisms experienced a drop in population after 4 days of inoculation. and after 10 days, recovery was achieved only through enrichment. Field survival of microorganisms was affected by lettuce cultivar and better survival of Salmonella in comparison to E. coli O157:H7 was determined. Detection through real-time PCR was affected by duration of sample enrichment; shorter times (4–12 h) resulted in more false negatives, however after 18 h, detection was achieved in all samples. Red-pigmented lettuce cultivars caused inhibition of most PCR reactions. Preparation of tissue mass composites of 375 or 125 g in comparison to 25 g samples increased the rate of false negatives, the effect was pronounced when comparison was done between field-inoculated material compared to plant inoculated in the laboratory. In contrast, liquid compositing resulted a reliable strategy to reduce the number of molecular tests. Results highlighted the importance of specific commodity validation of molecular detection methods that consider sample matrix composition, natural microbiota and the cell stress of the pathogens.     

CAD数据文件加密技术的剖析

考察了一个小型CAD系统,对其数据文件进行了剖析,导出其数据文件的详细构造,并依据其文件结构编写了一个数据解密的样例程序供参考。     

The mechanical behaviour of weak mudstone (Opalinus Clay) at low stresses

Over the last 10 years argillaceous rocks (mudrocks), such as the Jurassic claystone Opalinus Clay, have gained acceptance as a potential host formation for geological disposal of nuclear waste. Observations from tunnels in Opalinus Clay at the Mont Terri rock laboratory, Switzerland, suggest that the excavation-induced response is not linear-elastic. The micro-structure of the Opalinus Clay has been identified as a source for this response. It has been demonstrated that diagenetic processes over the last 180 Ma have been responsible for the formation of strong diagenetic bonds locking latent strain energy into the micro-structure of Opalinus Clay. A conceptual model of the micro-structure, including the effects of diagenetic processes, has been developed as a framework to interpret the mechanical behaviour of the Opalinus Clay. Samples recovered at Mont Terri rock laboratory have been subjected to processes that have resulted in bond breakage and the release of locked-in latent strain energy. This tends to reduce the strength and deformation properties of samples and induces low stiffness non-linearity of the stress–strain curve at low stress levels. Numerical modelling of the sampling stress-path at Mont Terri rock laboratory shows that unloading was the dominant factor resulting in this response. As a result, samples can shed light on the unloading response of the rockmass to excavation. This non-linear behaviour has been quantified by means of routine laboratory compressive tests.     

PARAMETER ESTIMATION FOR 2-PARAMETER LOG-LOGISTIC DISTRIBUTION (LLD2) BY MAXIMUM ENTROPY

The principle of maximum entropy (POME) was employed to derive a new method of parameter estimation for the 2-parameter log-logistic distribution (LLD2). Monte Carlo simulated data were used to evaluate this method and compare it with the methods of moments (MOM), probability weighted moments (PWM), and maximum likelihood estimation (MLE). Simulation results showed that POME's performance was superior in predicting quantiles of large recurrence intervals when population coefficient of variation was greater than or equal to 1.0. In all other cases, POME's performance was comparable to other methods. In terms of parameter bias and root mean square error, POME was comparable to MLE and superior to both MOM and PWM.     

Examining the Suitability of the Reaction Engineering Approach (REA) to Modeling Local Evaporation/Condensation Rates of Materials with Various Thicknesses

The reaction engineering approach (REA) is examined here to investigate its suitability as the local evaporation rate to be used in multiphase drying. For this purpose, REA is first implemented to model the convective drying of materials with various thicknesses. The relative activation energy, as the fingerprint of REA, generated from one size of a material is used to model the convective drying of the same material with different thicknesses. Because the results indicate that REA parameters can model the drying of materials with various thicknesses, REA can be scaled down to describe the local evaporation rate (at the microscale as affected by local composition and temperature). The relative activation energy is used to describe the global drying rate in modeling the local evaporation rate. REA is combined with a system of equations of conservation of heat and mass transfer in order to yield the spatial reaction engineering approach (S-REA) as a nonequilibrium multiphase drying model. By using S-REA, the spatial profiles of moisture content, concentration of water vapor, temperature, and local evaporation rate can be generated, which can assist in comprehending the transport phenomena.     

基于预处理的水样检测结果分析

水样预处理过程中的不同处理方法或者说操作步骤对氨氮分析结果的影响有重要的影响,实验分析水样预处理方法对氨氮分析结果产生的影响,希望本实验的结果和分析能为实验操作人员提供一些有用的数据和经验,给广大实验操作者提供比较明确的数据和结论,以使操作人员能清晰判断要预处理与否并对水样进行合理的预处理操作。     

A discrete-time amplifier based on Thin-Film Trans-Capacitors for sensor systems on foil

Organic materials can be used to fabricate sensors for physical and chemical quantities, and also to make electronics. The integration of these two elements holds the promise to enable novel smart-sensors on foil. In this paper, we deal with the design of the first stage of a signal conditioning chain on foil: the amplifier. The poor electrical performance of organic TFTs hampers the design of complex circuits, and negatively affects the characteristics of continuous-time amplifiers. In order to improve small-signal gain and speed, a mixed discrete-time and continuous-time approach is presented in this paper for the sensor frontend. A new device, the Thin-Film Trans-Capacitor, is presented and used to build the discrete-time amplifier, while the continuous time amplifier exploits a simple traditional architecture to improve yield. Simulations of the circuit proposed show that the total gain of the sensor frontend increases of about one decade without any detrimental effect on the speed. CAD (Computer-Aided Design) simulations confirm the results of the simple mathematical model we present.     

Real-time monitoring of events applied to syndromic surveillance

Abstract

This article focuses on monitor plans aimed at the early detection of the increase in the frequency of events. The literature recommends either monitoring the time between events (TBE) if events are rare or counting the number of events per unit non-overlapping time intervals otherwise. Some authors advocate using the Bernoulli model for rare events, applying presence or absence of events within non-overlapping and exhaustive time intervals. This Bernoulli model does improve the real-time monitoring assessment of these events compared to counting events over a larger interval, making them less rare. However this approach became inefficient if more than one event starts occurring within the intervals. Monitoring TBE is the real-time option for outbreak detection, because outbreak information is accumulated when an event occurs. This is preferred to waiting for the end of a period to count events. If the TBE reduces significantly, then the incidence of these events increases significantly. This article explores this TBE option relative to using the monitoring of counts when the TBEs are either Exponentially, Gamma or Weibull distributed for moderately low count scenarios. The article will discuss and compare the approaches of using an Exponentially Weighted Moving Average (EWMA) statistic for the TBEs to the EWMA of counts. Several robust options will be considered when the future change in event frequency is unknown. Our goal is to have a robust monitoring plan which is able to efficiently detect many different levels of shifts. These robust plans are compared to the more traditional event monitoring plans for both small and large changes in the event frequency.